Bottom Line:
We also compared several life history traits for 25 lines with large and 25 lines with small genomes in three thermal environments, and found that genome size as well as genome size by temperature interactions significantly correlated with survival to pupation and adulthood, time to pupation, female pupal mass, and female eclosion rates.Expression data implicate differences in metabolism that correspond to genome size variation.These results indicate that significant genome size variation exists within D. melanogaster and this variation may impact the evolutionary ecology of the species.

Affiliation: Department of Entomology, Texas A&M University, College Station, Texas, United States of America.

ABSTRACTWe determined female genome sizes using flow cytometry for 211 Drosophila melanogaster sequenced inbred strains from the Drosophila Genetic Reference Panel, and found significant conspecific and intrapopulation variation in genome size. We also compared several life history traits for 25 lines with large and 25 lines with small genomes in three thermal environments, and found that genome size as well as genome size by temperature interactions significantly correlated with survival to pupation and adulthood, time to pupation, female pupal mass, and female eclosion rates. Genome size accounted for up to 23% of the variation in developmental phenotypes, but the contribution of genome size to variation in life history traits was plastic and varied according to the thermal environment. Expression data implicate differences in metabolism that correspond to genome size variation. These results indicate that significant genome size variation exists within D. melanogaster and this variation may impact the evolutionary ecology of the species. Genome size variation accounts for a significant portion of life history variation in an environmentally dependent manner, suggesting that potential fitness effects associated with genome size variation also depend on environmental conditions.

pgen-1004522-g002: Genome size and temperature affect D. melanogaster development and plasticity.Only phenotypes with significant R2 values (the proportion of variation in each phenotype due to genome size variation, not accounting for other genetic effects) are depicted. The average survival to pupation (A), minimum pupation time (B), female pupal mass (C) and female eclosion time (D) is shown for the 25 strains with the largest and smallest genomes at 20°C (blue triangle), 25°C (green circle), and 30°C (red square). Plasticity for minimum pupation time (E), female pupal mass (F) and female eclosion time (G) is shown between 20°C and 30°C (turquoise diamond), 20°C and 25°C (purple x) and 25°C and 30°C (orange star). Dashed lines represent 95% confidence intervals of the regression line.

Mentions:
In order to take advantage of the observed variation in genome size among inbred strains and examine the life history effects of an increase or decrease of genome size, we reared 25 strains with large female genomes and 25 strains with small female genomes (Table 1) at three temperatures (20°C, 25°C, and 30°C) and scored life history traits for each strain at each temperature (Figures 1, 2, S3; Table S1). A significance test across all genome size means of 211 strains derived from 1,052 measurements showed the 25 strains with the large genomes differed significantly from the 25 strains with the small genomes (Table 1) (t-test; P<0.001). The life history traits of survival to pupation, minimum pupation time, female pupal mass, and female eclosion time varied significantly across strains and temperatures (Figures 1, S3; Table S1). Survival to pupation strongly correlated with survival to adulthood (r = 0.975); therefore, we report only survival to pupation.

pgen-1004522-g002: Genome size and temperature affect D. melanogaster development and plasticity.Only phenotypes with significant R2 values (the proportion of variation in each phenotype due to genome size variation, not accounting for other genetic effects) are depicted. The average survival to pupation (A), minimum pupation time (B), female pupal mass (C) and female eclosion time (D) is shown for the 25 strains with the largest and smallest genomes at 20°C (blue triangle), 25°C (green circle), and 30°C (red square). Plasticity for minimum pupation time (E), female pupal mass (F) and female eclosion time (G) is shown between 20°C and 30°C (turquoise diamond), 20°C and 25°C (purple x) and 25°C and 30°C (orange star). Dashed lines represent 95% confidence intervals of the regression line.

Mentions:
In order to take advantage of the observed variation in genome size among inbred strains and examine the life history effects of an increase or decrease of genome size, we reared 25 strains with large female genomes and 25 strains with small female genomes (Table 1) at three temperatures (20°C, 25°C, and 30°C) and scored life history traits for each strain at each temperature (Figures 1, 2, S3; Table S1). A significance test across all genome size means of 211 strains derived from 1,052 measurements showed the 25 strains with the large genomes differed significantly from the 25 strains with the small genomes (Table 1) (t-test; P<0.001). The life history traits of survival to pupation, minimum pupation time, female pupal mass, and female eclosion time varied significantly across strains and temperatures (Figures 1, S3; Table S1). Survival to pupation strongly correlated with survival to adulthood (r = 0.975); therefore, we report only survival to pupation.

Bottom Line:
We also compared several life history traits for 25 lines with large and 25 lines with small genomes in three thermal environments, and found that genome size as well as genome size by temperature interactions significantly correlated with survival to pupation and adulthood, time to pupation, female pupal mass, and female eclosion rates.Expression data implicate differences in metabolism that correspond to genome size variation.These results indicate that significant genome size variation exists within D. melanogaster and this variation may impact the evolutionary ecology of the species.

Affiliation:
Department of Entomology, Texas A&M University, College Station, Texas, United States of America.

ABSTRACTWe determined female genome sizes using flow cytometry for 211 Drosophila melanogaster sequenced inbred strains from the Drosophila Genetic Reference Panel, and found significant conspecific and intrapopulation variation in genome size. We also compared several life history traits for 25 lines with large and 25 lines with small genomes in three thermal environments, and found that genome size as well as genome size by temperature interactions significantly correlated with survival to pupation and adulthood, time to pupation, female pupal mass, and female eclosion rates. Genome size accounted for up to 23% of the variation in developmental phenotypes, but the contribution of genome size to variation in life history traits was plastic and varied according to the thermal environment. Expression data implicate differences in metabolism that correspond to genome size variation. These results indicate that significant genome size variation exists within D. melanogaster and this variation may impact the evolutionary ecology of the species. Genome size variation accounts for a significant portion of life history variation in an environmentally dependent manner, suggesting that potential fitness effects associated with genome size variation also depend on environmental conditions.